If KRA is not enabled from the self login , please check below mentioned points.
Check whether HR has uploaded KRA in the system or not.
Please go to below path and check Goal Start and End date
Configuration >> HRMS >> PMS periods >> select PMS period from the
Select PMS Period as required then check Goal start and End date
If employee’s submission do not fall within Goal Start and End date then you can modify the date so that employee can fill PMS form and Self rating will get enabled.